The aim of this protocol was to determine in diabetics the effect of giving wheat amylase inhibitor for 1 week on blood glucose and gastrointestinal hormones. Six diabetics were fed a standard weight maintenance diet for 3 weeks. During week I, usually therapy for diabetes mellitus was continued. Wheat amylase inhibitors and diabetic medications were withheld during the third week. On days 7, 14, and 21, blood was drawn before and every 1/2 hour for 4 hours postprandially for blood glucose, c-peptide and HPP. During week II (compared to week III), the delta blood glucose (area under the curve) and concentrations of c-peptide and HPP were lower in response to dinner. One patient developed loose stools on wheat amylase inhibitors that improved by day 6. Wheat amylase inhibitor lowers blood glucose in diabetes mellitus, more so with larger meals. Wheat amylase inhibitor is potentially useful and safe therapy for diabetes mellitus; however, long-term studies in more diabetics are needed to confirm the efficacy and safety of the wheat amylase inhibitor.